A merged gain-variable RF front-end design for a 2GHz WCDMA DCR application I

A merged variable gain differential CMOS LNA and mixer is proposed for a 2GHz WCDMA DCR application. Variable gain stage is placed before frequency down-mixing stage to increase system dynamic range. To increase LO to RF isolation, thus to overcome DC-offset problem, we use 0.18/spl mu/m triple-well CMOS process. The system shows 25dB and 12.5dB conversion gain at high gain mode and low gain mode respectively. In each case, the IIP2s are 18dBm and 29dBm, and IIP3s are 3dBm and 11dBm respectively. The overall power consumption is less than 18mW. The supply voltage is 1.8V and over-all chip size is 2.3mm/spl times/1.2mm.

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